Stethoscope.



.No. 872,448. PATENTED DEC. 3, 1907. D. P. PBNHALLOW.

STETHOSCOPE.

APPLICATION run!) In. 2, 1901.

ITLUBTIZO? Jan 20:70 Pearce 7%): 723115000 DUNLAP PEARCE PENHALLOW, OF BOSTON, MASSACHUSETTS.

STETHOBCOPE.

Specification. of Letters Patent.

Application filed January 2. 1907. Serial No. 850.498.

To all whom it may concern:

Be it known that I, DUNLAP PEARCE PEN- HALLOW, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Stethoscopes, of which the following is a specification.

This invention relates to stethoscopes, and its principal object is so to construct such a.

instrument that it can be used in examinations of bedridden patients without requiring either that the patient should be'moved or raised or that the bed-clothing should be removed.

Other ob'ects are to provide anim roved means for detachabl sec a diap n' over the mouth of t e cavity of the stethoscope, and in so constructing such cavity that improved results as to transmission of sounds are obtained, all as will more fully appear from the specification with reference to the accompanying drawings forming a part thereof in which,

Figure 1 re resents an elevation of a stethoscope embo ying the principles of my invention. Fig. 2 represents a side elevation on an enlarged scale, of the cup or body portion of the stethoscope. F i 3 represents a longitudinal section throug the center of the cup, the same being taken on line 33 of The same reference characters indicate the same parts in all the figures.

In the drawings,-a represents the body portion or cup of the stethosco e which is c lindrical or circular in front e evation, as sl lown by Fig. 1, and is of relatively slight depth or thickness. In the front face of the cup isformed a recess or cavity 1), while the back 0 is imperforate and smooth throu hout its whole extent without projections, in entations or other irregularitles of any kind. As the cup is formed from a single block of metal, the back is rigid and not readily vibrated, and at its periphery it is beveled so that it merges into the cylindrical sides on a curve of lar e radius. V

Across t e 0 ening of the cavity 6 is stretched a diap agm d, the ed es of which are drawn over the end of the ody a and clamped to the sides thereof by a spring ring e, which presses the diaphragm into a groove f formed externally on the cylindrical por tion of thecup adjacent the edges thereof. This ring is discontinuous, being divided or split at 9 (see Fig. 1), and can be expanded so l as to be slipped on or off over the edge of the cup a, whi e its resiliency causes it to contract and clamp-the edges of the diaphragm tightly in the groove The diaphragm preferably is made of a somewhat elastic material which will vibrate easily when stretched, such as sheep-skin, rubber or the like, and can very readily be secured in place or removed by slmply sliplpinii the e on or off. In first 66 app ylng t e aphragm, when the latter is o sheep-skin, it 1s first wet, which causes it to expand and become soft, and is stretched across the opening of the cavity with its edges turned up over the sides of the cup. 70 The ring is then slipped on to hold it in place. In drying, the diaphragm shrinks and becomes stiff and tightly stretched.

At-one side of the cup a is formed a fixed tube It having a passage '5 which opens into the cavity 1) so as to form an outlet for conducting away the sound vibrations produced therein by the vibrations of the diaphra (1 when the latter is pressed against the liily of a person. This tube is preferably united to the cup-by being ushed mto a lateral passage cut through t e side of the cup and opening into the cavit b. When in place t e tube is soldered so t at it cannot be withr drawn, and thus becomes a rigid, fixed, and to all intents and pm ses an inte a1 part of the stethoscope 3y. It might e possible in some circumstances to form the tube integrally from the same iece of metal as the cup, but the metho of construction above described is the preferable one. The end of the tube It is rovided with corru ations adapted to retain the end of a flexi le tube j whlch may be slipped over it. To the flexible tube is connected in the usual manner, two tubes is for conduct' the sounds to the ears of the user of the stlifioscope, which tubes are provided with the usual ear tips I. From F1g. 3, which shows a section taken throu h the center of the cup, it will be seen that t e elements 1) b of the walls of the recess or cavity are straight lines converging nearly at right angles at the point where the back 0 has the least thickness. Similarly, a section taken on any other diameter of the cup would show the walls as straight lines converging toward the same point. The walls or bounding surfaces of the cavity thus are. seen to be conical.

The comparatively slight thickness of the 110 stethoscope body, the outlet tube extendin from the side instead of the back thereof, an

, the patient.

.under the bed-clothing or beneath the the rigid smooth back having rounded edges, enable'the instrument to be easily slippgd 0 of a patient who is in such a condition tha t changing of the position is impossible or highly undesirable. The ordinary stethoscope which has its sound-conducting tube extendin directly from the back cannot be a used in t lis manner, except with great diffiv ere with the sounds caused by the organ being examined. As the body of mylnstrument has a rigid, non-vibratory back, the friction sounds are minimized and so reduced as to be almost inaudible. Then a ain,-- the outlet tube coming from the side 0 the cup, and being perfectly rigid, is not ,SUSCGP-K tlble to vibrations due to friction, and so does not transmit any friction sounds.

From Fig. 1, which shows the .bodyv of the stethoscope in its actual size, and Figs. 2 and 3, which show it enlarged totwice the actual size, it will be seen that all the dimensions are very small, and that therefore it can be slipped into small spaces without disturbing Furthermore, the small area of the diaphragm enables sounds produced by diflerent organs to be exactly located, and

permits aural examination to be made of the apices of the lungs, a result which is not posslble with any instrument of this character of which I have knowledge. This feature also causes the sounds from any particular part to be transmitted with the maximum distinctness and without confusion by sounds emanating from another organ or parts of. an organ than that immediately under examination. The small size also permits the instrument to be contained in a small space and easily carried by the possessor. The body also has a comparatively thick rim sur-'- rounding the cavity, as is evident from Fig. 3, and this gives not only rigidity, but also relatively great weight, so that when placed upon the body of a person being examined, the weight alone holds it firmly against the skin of the patient without requiring much pressure from the fingers of the user.

One of the principal causes of the increased efficiency of this instrument I attribute to the conical formation of the cavityabove described, which condenses the sound waves and brings them to a sharper and 'soundsmore clearly is in part caused clearer focus than is the case when the cavity is spherical or the walls are otherwise curved. It also permits of no angles or pockets bein formed to impede the progress of the soun waves. The result of transmittin the hy the fact that the passage 41 extends straight from one side of the cavity as near the focus thereof as it can be placed, with one of its sides.

in line with the bottom of the cavity, and without any bends or angles. As it makes a very large obtuse angle with the wall I) of the cavlty opposite the openin .intothe passage (practically the same ang e as that made wit the same wall b the axis of the body a,for the conical walls he approximately at angles of 45 (with the axis), the sounds are reflected by this wall directly into the passage without diminution. As a matter of fact, I have found by observation that the sounds received through this instrument are much sharper, clearer and much more distinct than is the case with other stethoscoes.

other result from having the tube led off from the side of the cup is that thereby the latter may be made relatively thin from face to back, while at the same time, thecavity may be of greater depth and the walls thereof more steeplyinclined (whereby -a sharper focus of the sound waves is obtained) than is possible with those instruments wherein the passage extends from the back of the cavity and is then curved toward the side'. r

The manner of securing thediaphra m in place not only permits a ready remova and substitution of a new diaphragm, in case one becomes broken or injured, but also, the fact that the edges of the diaphragm are wra ped over the rim of the cup1 and secured y a ring at a distance from -t e edge of the latter instead of by an annularcap, prevents the metal part of the stethoscope coming into contact with the flesh of a patient, and so guards against causing a chill when the metal is cold. The presence of the diaphragm also.causes the air in the cavity and tubes up to the ears of the user to be at a constant ressure, and prevents inflow or outflow 0 any of the air. Thereby any v1- bration, even the slightest, sets the air column in the tubes into vibration, and transmitsthe sounds clearly to the observers ears.

Finally, the device is one of extreme simplicity, consisting only of three 'parts (exclusive of the tubes and ear pieces which are common to all Stethoscopes), and being only the body a with the r1gid tube, the diaphragm, and the clamplng ring. This of course minimizes the chance of loss of parts of the device, since there are only a few parts which can be lost, and enables it to be put readily into condition for use.

I I claim i" 1 A stethoscopeconsisting of a cup formed from a solid block with a cavity in oneface, the elements of the bounding walls of said cavity being straight from end to end and converging from the edges of the block to a sharp apex near the opposite face, and a straight tube extending into one side of the block and opening at the apex of the cavity.

2. A stethosco e consisting of a cup made from a solid blocii of metal with a cavity in one face, the bounding walls of which form a conical surface converging to a sharp apex, and are straight from the apex to the edges, and a straight tube extending into one side of the block and opening at the apex, the

walls of the cavity making substantially 15 egnal angles with the axes of the tube and o the cavity, whereby the sound waves are gathered into a sharp and distinct focus and reflected directly through the tube.

In testimony whereof I have aflixed my 20 signature in presence of two witnesses.

DUNLAP PEARCE PENHALLOW.

Witnesses. I I

BELLE R. NEWTON, CALVIN S. TILDEN. 

